1. Technical Field
The present invention relates to a liquid ejecting head unit and a liquid ejecting apparatus that eject a liquid from nozzles; in particular, the invention relates to an ink jet recording head unit and an ink jet recording apparatus that discharge ink as the liquid.
2. Related Art
The ink jet recording head unit that discharges ink droplets is a representative example of the liquid ejecting head unit that ejects the liquid. As the ink jet recording head unit, there has been proposed (for example, refer to JP-A-2009-6730) an ink jet recording head unit that includes, for example, an ink jet recording head that discharges ink droplets from nozzles, and a flow path member that is fixed to the ink jet recording head and supplies ink from a liquid storage portion such as an ink cartridge that the ink is stored in, to a liquid ejecting head.
The flow path member of the ink jet recording head unit includes an upstream flow path member to which the ink from the liquid storage portion is supplied, and a downstream flow path member that holds the ink jet recording head and supplies the ink from the upstream flow path to the ink jet recording head. The flow path member is configured to interpose a seal member, which is formed of an elastic material of a plate shape such as a sheet, between the upstream flow path member and the downstream flow path member, and therefore be sealed such that the ink does not spill from the connected flow paths.
However, there are problems, in that when the flow path that is connected at the upstream flow path and the downstream flow path is to be sealed using a seal member formed of an elastic material such as a rubber sheet that is interposed between two members, a pressure is applied in a direction in which the upstream flow path member and the downstream flow path member separate from one another and a pressure is applied in a vertical direction to a liquid ejecting surface, through which the ink ejecting head discharges the ink droplets, due to a repulsive force caused by the elastic deformation of the seal member. This causes problems to occur, such as landing misalignment of the ink droplets to an ejecting target medium, caused by peeling between the flow path member and the liquid ejecting head, peeling of laminated members that constitute the liquid ejecting head, and warping of the liquid ejecting surface of the liquid ejecting head.
To deal with the problems described above, a configuration has been proposed in which the two flow paths are provided within a pipe-shaped portion, both of which are connected by a tube-shaped seal member, as disclosed in JP-A-2003-305873. However, there is a problem in that when the pressure with which the seal member abuts the pipe-shaped portion is low, the ink leaks out. There is also a problem in that, when fitting the tube-shaped seal member onto the pipe-shaped portion, the seal member stretches; thus, the sealing strength is reduced and the ink leaks out. Furthermore, there is a problem in that the ink also leaks out due to degradation of the tube-shaped seal member with the passage of time. Such leaking out of the ink occurs particularly due to the seal member expanding when the ink is supplied under pressure.
There is also a problem in that, irrespective of whether a plate-shaped or a tube-shaped seal member is used, when the upstream flow path member and the downstream flow path member are assembled, it is necessary to push the upstream flow path member relative to the downstream flow path member. There is a concern that a pressure will be applied in a direction in which the upstream flow path member and the downstream flow path member separate from one another due to the pushing.
On the other hand, there is a problem in that, when the pipe-shaped portion and the tube-shaped seal member are caused to be sealed by causing them to abut one another with a high pressure, the tube has to be fitted onto the pipe-shaped portion with a high pressure. Therefore, a problem occurs, such as a reduction in ease of assembly, and landing misalignment of the ink droplets caused by destruction of the liquid ejecting head or warping of the liquid ejecting surface due to a pressure being applied to the liquid ejecting head during the fitting.
Note that, the problems described above are not limited to the ink jet recording head unit, and are also present in a liquid ejecting head unit that ejects a liquid other than ink.